Does Maternal Warmth Moderate the Effects of Birth Weight on Twins' Attention-Deficit/Hyperactivity Disorder (ADHD) Symptoms and Low IQ?

Influence of naturally occurring variations in maternal care on prepulse inhibition of acoustic startle and the medial prefrontal cortical dopamine response to stress in adult rats

In rats, naturally occurring variations in maternal care contribute to the development of individual differences in the behavioral and neuroendocrine responses to stress during adulthood. The dopamine (DA) projection to the medial prefrontal cortex (mPFC) plays an important role in mediating stress responsivity and is thought to be involved also in regulating sensorimotor gating. In the present study, we compared prepulse inhibition (PPI) of acoustic startle as well as the left and right mPFC DA stress responses in the adult offspring of high- and low-licking/grooming (LG) dams. Our data indicate that the offspring of low-LG animals are impaired on measures of PPI compared with high-LG animals. We also observed in low-LG animals a significant blunting of the mPFC DA stress responses that was lateralized to the right hemisphere, whereas in high-LG animals, the left and right mPFC DA stress responses were equally attenuated. Although mPFC levels of DA transporter did not differ between the two groups of animals, mPFC levels of catechol-O-methyl transferase immunoreactivity of low-LG animals were significantly lower than those of high-LG animals. These data provide evidence that variations in maternal care can lead to lasting changes in mPFC DA responsivity to stress and suggest the possibility that such changes in mesocorticolimbic DA function can also lead to deficits in sensorimotor gating.

Developmental trajectories of conduct problems and hyperactivity from ages 2 to 10

BACKGROUND

Conduct problems (CP) and hyperactivity/attention problems (HAP) are thought to covary with regularity, yet few studies have examined their co-occurrence or risk factors that discriminate their trajectories beginning in early childhood.

METHOD

The present study sought to advance our understanding of this issue by examining separate trajectories of overt CP and HAP symptomatology among 284 boys from urban, low-income families followed from ages 1.5 to 10. We also investigated the co-occurrence of persistent CP and HAP and explored risk factors that discriminate CP and HAP trajectories.

RESULTS

Four similar trajectory groups were identified for both CP and HAP symptoms. Chronic CP was differentiated from persistent low CP by risk factors in child, parenting, and family domains, while chronic trajectories of HAP were typified by elevated maternal depressive symptoms compared to children with persistent low HAP.

CONCLUSIONS

The findings extend previous research with older children of HAP and/or CP, highlighting the effects of proximal family and child risk factors that are identifiable in the first two years of children's lives and associated with trajectories of disruptive behavior.